CT scanners are widely used for cross-sectional imaging of the body. CT scanners which are presently available are capable of measuring a proposed trajectory for a biopsy needle or drainage catheter including the estimated depth and angle.
Most radiologists use a visual approximation of the optimal angle of the biopsy catheter/needle during the procedure. Current CT scanners provide laser guidance to choose the entry point on the skin. However, that does not guide the radiologist to choose the correct angle for the biopsy. Vertical trajectory at a 90-degree angle does not always provide an accurate access method. There may also be organs such as bowel, liver, heart, or kidney between the access point and the target. Thus, the needle needs to be manipulated by the radiologist to obtain access to the target.
Most radiologists perform CT-guided procedures by choosing the entry point on the skin and placing grid lines on the skin. CT lasers and grids thus help to identify the entry point. Then, the radiologist advances the needle slowly at an approximate estimation of the desired angle. Multiple individual small volume acquisitions of CT images are obtained throughout the procedure to determine the actual position of the needle or catheter and altering its trajectory as needed. Normally, radiologist may need a minimum of 3 to 4 CT acquisitions to obtain a tissue sample from the target
This trial-and-error technique has major disadvantages. Firstly, it usually requires the patient to remain in a fixed position, lying supine or prone for a relatively long period of time, which most patients find uncomfortable. Secondly, the increased radiation dose from the multiple CT image acquisitions is potentially harmful to the patient. Additionally, in practices where CT access is limited, a relatively lengthy procedure will delay other CT examinations.
As such, considering the foregoing, it may be appreciated that there continues to be a need for novel and improved devices and methods for guiding a needle during CT guided biopsy and drainage procedures.